How to add a vertical bar on a panel?

Question

I'm simply trying to add a vertical bar that can go from top to bottom on the right side of my panel. I would prefer to have a class instead of an in-line css style. Can anyone tell me what I'm missing, please? Thanks a lot in advance!

NOTE:

• I want a div inside my p-panel to make the vertical bar

Here's my code:

PLUNKER

<p-panel>
 <p-header>
    Title
</p-header>

  <textarea [rows]="5" [cols]="30" pInputTextarea autoResize="autoResize"></textarea>
  <div class = "my-class"></div>

</p-panel>

Here's a pic of what I want:

Answer 1

Here you go: https://plnkr.co/edit/K3SQnzRBjuZMRH0P61u3?p=preview

.ui-panel {
  position: relative !important;
}

.my-box {
  position: absolute; 
  right: 3px; 
  top: 3px; 
  bottom: 3px; 
  width: 40px; 
  background: red;
}